Effects of Oxygen Breathing on the Heart Rate, Blood Pressure, and Cardiac Index of Normal Men—resting, With Reactive Hyperemia, and After Atropine*

known quantity of dye + 0.05 mg. All injections were made during the end-expiratory phase of respiration. A Harvard withdrawal pump was used to draw blood through a Waters XP-100A densitometer from the brachial arterial needle at a rate of 19.4 ml per minute.